In usr.bin/sort, use another method of silencing warnings about unused arguments, which does not trigger self-assignment warnings in certain circumstances (for example, using clang with ccache).
In usr.bin/sort, use another method of silencing warnings about unused
arguments, which does not trigger self-assignment warnings in certain
circumstances (for example, using clang with ccache).

MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase